The Major League Soccer club acquired Rusin on Friday pending receipt of his international transfer certificate and visa. Rusin played 38 games for Denmark's HB Koge after spending two-plus seasons under Rennie with the Carolina RailHawks of the North American Soccer League.
"Brad is a very powerful, athletic player who can play a couple of different positions," Rennie said. "He did very well in Denmark and had a lot of interest from clubs in Europe and other clubs in MLS.
"We are pleased that we've got him and think that he can be an important player for us right away, but also for the long term."
Rusin, a 26-year-old American, had three goals over parts of two seasons with HB Koge. The team played in the Danish Superliga in 2011 and moved to the Danish First Division the following year.